摘要：Ab initio total energy calculations are used to determine the interface structure of GaN films grown on 6H-SiC(0001)with different substrate *** results indicate that GaN films grown on bare SiC(0001)are of the Ga-polarity,while GaN films grown on SiC(0001)with Si adlayer are of the N-polarity if there is no N-Si interchange at the *** the interchange,the GaN films are of the Ga-polarity.